title: MiR-145 functions as a tumor-suppressive RNA by targeting Sox9 and adducin 3 in human glioma cells.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are increasingly being recognized as being involved in cancer development and progression in gliomas.
  
  
  METHODS
  Using a model cell system developed in our lab to study glioma progression comprising human neuroglial culture (HNGC)-1 and HNGC-2 cells, we report here that miR-145 is one of the miRNAs significantly downregulated during malignant transformation in glioblastoma multiforme (GBM). In a study using tumor samples derived from various glioma grades, we show that expression of miR-145 is decreased in a graded manner, with GBM patients showing lowest expression relative to lower-grade gliomas (P < .05) and normal brain tissues (P < .0001). Functional studies involving ectopic expression of miR-145 in glioma cells had a negative impact on cell proliferation and tumor development, as well as invasion and induced apoptosis, providing further support to the concept that inactivation of miR-145 is important for glioma disease pathogenesis. More notably, these growth-suppressive effects of miR-145 are mediated through its target proteins Sox9 and the cell adhesion-associated molecule adducin 3 (ADD3).
  
  
  RESULTS
  Inhibiting Sox9 and ADD3 rescued effects of miR-145 loss. Interestingly, miR-145 loss in glioma cells led to overexpression of molecules involved in cell proliferation, like cyclin D1, c-myc, and N-myc, as well as enhanced expression of cell adhesion- and invasion-related molecules N-cadherin and E-cadherin, an effect which was again restored upon miR-145 overexpression in glioma cells. The miR-145 promoter was methylated at its cytosine-phosphate-guanine (CpG) islands in the glioma cell lines studied.
  
  
  CONCLUSIONS
  Our study demonstrates that miR-145 has a tumor-suppressive function in glioblastoma in that it reduces proliferation, adhesion, and invasion of glioblastoma cells, apparently by suppressing the activity of oncogenic proteins Sox9 and ADD3. Reduced levels of miR-145 may lead to neoplastic transformation and malignant progression in glioma due to unregulated activity of these proteins.
authors.affiliation: Corresponding Author: Anjali Shiras, MSc, PhD, Scientist-F, National Centre for Cell Science (NCCS), NCCS Complex, University of Pune Campus, Ganeshkhind, Pune 411007, Maharashtra, India. anjalishiras@nccs.res.in; anjalishiras@gmail.com.
authors.forename: Sandhya B
authors.initials: SB
authors.lastname: Rani
authors.forename: Sachin Shivaji
authors.initials: SS
authors.lastname: Rathod
authors.forename: Shanmuganandam
authors.initials: S
authors.lastname: Karthik
authors.forename: Navjot
authors.initials: N
authors.lastname: Kaur
authors.forename: Dattatraya
authors.initials: D
authors.lastname: Muzumdar
authors.forename: Anjali S
authors.initials: AS
authors.lastname: Shiras
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002148:Calmodulin-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion; D002453:Cell Cycle; D002465:Cell Movement; D049109:Cell Proliferation; D005910:Glioma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D035683:MicroRNAs / Q000235:genetics*; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055758:SOX9 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D000099291:Adducins
chemical_list: D002148:Calmodulin-Binding Proteins; D035683:MicroRNAs; D012333:RNA, Messenger; D055758:SOX9 Transcription Factor; C102021:ADD3 protein, human; D000099291:Adducins; C541010:MIRN145 microRNA, human; C527932:SOX9 protein, human
keywords: Sox9; adducin 3; glioma stem cells; invasion; neoplastic transformation; promoter methylation